Google has been hit by a setback in a patent row with Hyperphrase Technologies, LLC. A federal appeals court in Wisconsin yesterday rejected part of a summary judgment that could have worked to Google's advantage in the case.

In June last year the search engine giant was slapped with a lawsuit in which Madison-based software firm Hyperphrase Technologies, LLC and Hyperphrase Inc claimed that Google had infringed four patents used to make AutoLink and AdSense.

The district court in Wisconsin later rejected the case and granted summary judgement in favour of Google.

But the US Court of Appeals for the Federal Circuit said it, in fact, partially upheld the summary judgment, partially vacated it and remanded the case for further proceedings in the district court.

The federal appeals court agreed that Google's AdSense tool did not infringe upon Hyperphrase's patents.

However, it was divided in the case of AutoLink. It said that Google did not infringe on one of the Hyperphrase patents, but the court vacated a summary judgment in favour of Google on two others, thereby slinging the case back into the arms of the district court.

Google's managing counsel for litigation Michael Kwun said:

"We're very pleased that the Federal Circuit agreed that AdSense does not infringe any of Hyperphrase's patents. We continue to believe the remaining claims in the lawsuit are without merit, and will vigorously defend against those claims."

This is not the first time Hyperphrase has attempted to sue a software giant. In 2003 it filed an intellectual property lawsuit against Microsoft in which it alleged the infringement of three patents used in Office XP and claimed $2bn in damages.

But Hyperphrase lost that particular battle with the district court ruling in favour of Redmond.